um-ubd: Entrust re-queue to the upper layers

Fixes crashes due to ubd requeue logic conflicting with the block-mq
logic. Crash is reproducible in 5.0 - 5.3.

Fixes: 53766defb8c8 ("um: Clean-up command processing in UML UBD driver")
Cc: stable@vger.kernel.org # v5.0+
Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 6 insertions, 2 deletions

diff --git a/arch/um/drivers/ubd_kern.c b/arch/um/drivers/ubd_kern.c
index 612535cd9706..6627d7c30f37 100644
--- a/arch/um/drivers/ubd_kern.c
+++ b/arch/um/drivers/ubd_kern.c
@@ -1403,8 +1403,12 @@ static blk_status_t ubd_queue_rq(struct blk_mq_hw_ctx *hctx,
 
         spin_unlock_irq(&ubd_dev->lock);
 
-        if (ret < 0)
-                blk_mq_requeue_request(req, true);
+        if (ret < 0) {
+                if (ret == -ENOMEM)
+                        res = BLK_STS_RESOURCE;
+                else
+                        res = BLK_STS_DEV_RESOURCE;
+        }
 
         return res;
 }